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Article type: Cover
1992Volume 438 Pages
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Published: August 30, 1992
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Article type: Cover
1992Volume 438 Pages
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Article type: Appendix
1992Volume 438 Pages
App1-
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Article type: Index
1992Volume 438 Pages
Toc1-
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Article type: Index
1992Volume 438 Pages
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Article type: Index
1992Volume 438 Pages
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Hirozo MIHASHI, Xuechurig ZHU
Article type: Article
1992Volume 438 Pages
1-7
Published: August 30, 1992
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A mathematical model is proposed to represent creep deformation of concrete at elevated temperatures, since most of existing models are not available to unsealed concrete exposed to elevated temperatures. After surveying existing models, a double power law is recognized as a potential model to represent the creep deformation at elevated temperatures. Accordingly moisture dependence of parameters in the double power law is discussed on the basis of published experimental data and the mathematical formulation is presented. Finally, a Published creep test result is analyzed and the applicability of the proposed model is discussed.
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Noriaki NOMURA, Hirozou MIHASHI, Masanori IZUMI
Article type: Article
1992Volume 438 Pages
9-14
Published: August 30, 1992
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Relation of fracture process zone to tension softening behavior of concrete has been studied using two series of fracture energy tests ; one was for concrete with the various sizes of maximal aggregate and the other was in different concrete ages. A fracture energy component was defined and determined for the concrete by using data fit technique. The results indicate that the beginning of descending branch in the tension softening diagram corresponds to micro crack process and that the tail of tension softening is attributed to the bridging mechanism at the intersurface between the matrix and aggregates.
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Masatoshi YAMAZAKI
Article type: Article
1992Volume 438 Pages
15-22
Published: August 30, 1992
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The object of this experimental study is to clarify the effect of temperature declining rate of mass concrete on thermal crack occurrence of mass concrete wall structure restricted by foundation with high rigidity. Three specimens are prepared, and they have same experimental conditions except their cooling rates from high temperature to room temperature. Cracks observed when shutterings were removed from the specimen after the temperature history finished. Ages of crack occurrence were detected through the concrete strain gages embedded in the foundation. As a result, it is deduced that the temperature declining rate did not affect on the crack formation of the mass concrete.
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Kyoji TANAKA, Takayuki HIRAI, Hiroshi HASHIDA, Michio KOIKE
Article type: Article
1992Volume 438 Pages
23-29
Published: August 30, 1992
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Five kinds of sealing beads that were different in depth of their concavity were repeatedly extended and contracted by a fatigue machine. Cracks appeared in the corner or the center on the surfaces of some specimens. The time to cracking became clearly shorter on the speciments of deeper concave shapes. To know the reason of these results, the stress distribution on the stirfaces of sealing beads w;ere calculated by the boundary element method. It was concluded by the both experimental and analytical results that a durable cross-sectional shape of a sealing bead to fatigue is a slightly concave shape.
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Hidenori ONO, Yutaka YOKOYAMA, Takamasa MIKAMI, Mamoru HORIGUCHI, Seis ...
Article type: Article
1992Volume 438 Pages
31-38
Published: August 30, 1992
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This paper presents the method for evaluating duration of vibration, on judojyo floors. Firstly, a sensory test was conducted using scores of sample floors. Based upon the results of sensory test, evaluation scales were constructed. Secondly, physical characteristics of sample floors were measured. From the results of measurement, T_<V・D> and D_<max>+ T_<V・D> were calculated as the physical value which indicate duration length of human sensation. Thirdly, based upon relationship between evaluation scales and T_<V・D> or D_<max>+ T_<V・D>, evaluation indices were obtained. Lastly, evaluation method was presented, which is composed of measurement method of T_<V・D> or D_<max>+ T_<V・D> and the evaluation indices.
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Akiharu MIYAKE, Takeshi YOSHIMURA
Article type: Article
1992Volume 438 Pages
39-48
Published: August 30, 1992
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This study was made for investigating the mechanism of the onset of the aerodynamic excitation of suspended roof models mainly in a wind tunnel. It was observed in the experiment that the separated shear layer on stationary models rolled up in very faint vortices, and that the shear layer was greatly excited by the model motion in a range of wind speed centered around the onset wind speed of the excitation. Therefore, it can be concluded that the role for the occurrence of the excitation of models is played by ,the vortices that are formed originally on stationary models. and are greatly amplified by the model motion as the inverse of the obtained reduced frequency of vortex shedding equaled to the reduced onset wind speed.
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Hisashi NOZOE, Kaoru KUSAKABE, Tadahiro FUKUSUMI
Article type: Article
1992Volume 438 Pages
49-64
Published: August 30, 1992
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For single piles under vertical and horizontal ,vibrations, dynamic Winkler stiffnesses of subgrade reaction on pile circumference and at pile tip are proposed as simple expressions. A simplified estimation for vibrational characteristics of impedances and receptances at pile head presented by solving equations of motion of the pile as rod and Timoshenko's beam and by introducing the proposed subgrade reactions. It is verified that this method is sufficiently accurate in the practical situation from comparison with the rigorous and other solutions and this application to a building suported on piles in a case history is readily useful.
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Takuji KOBORI, Shuichi KAMAGATA
Article type: Article
1992Volume 438 Pages
65-73
Published: August 30, 1992
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The placement of the active controllers is one of most important issues in the research of the active seismic response control* So we analyse the multistory buildings with the active adjustable stiffness systems which connect the target floor and the ground. When the self-balancing adaptive control algorithm is adopted, the structural vibration is suppressed by the self-detuning property and the energy absorption of controllers. The extent of adjustable stiffness as well as the number and the position of controllers are evaluated from the numerical results of the seismic response. The suitable position of the active controllers is selected from the eight cases of placement. The nonstationary spectra and the amount of the absorbed energy verify the nonresonant control effect by the active controllers.
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Koji NARAOKA, Hiroshi KATUKURA
Article type: Article
1992Volume 438 Pages
75-81
Published: August 30, 1992
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A feedback-feedforward control algorithm which utilizes information on future input is presented. When input accelerations can be considered as the output of a vibration system, the input accelerations are determined by the past and future input time-histories of the vibration system. This means that we can regard the former component as the part of information on future input time-histories. In this case, we can propose a new method of feedback-feedforward control algorithm. Numerical calculations are done to demonstrate effectiveness of the method. It becomes clear that the proposed method has higher control efficiency than the velocity feedback control.
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Yasutsugu SUZUKI, Yukio NAITO, Kiyomi HORIKOSHI
Article type: Article
1992Volume 438 Pages
83-92
Published: August 30, 1992
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Model shaking table tests were conducted to study the dynamic response of an embedded structure which was affected by the plasticity of surrounding soil and dynamic earth pressure acting on embedded walls. A new method for analyzing the dynamic response of an embedded structure was developed. In this method, the material nonlinearity of surrounding soil was handled using the equivalent-linear method, and the geometrical nonlinearity of slide, contact and uplift which occur between a structure and soil was modeled on nonlinear connecting elements. Simulation was performed for the test results, and the accuracy and reliability of this method were confirmed.
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Hidekazu NISHIZAWA, Shinji TAKEUCHI, Kiyoshi KANETA
Article type: Article
1992Volume 438 Pages
93-103
Published: August 30, 1992
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A series of on-line tests using steel frame models with different natural period of vibration has been carried out and the experimental data had been examined from the view point of energy response.
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Koji UETANI, Tsuneyoshi NAKAMURA
Article type: Article
1992Volume 438 Pages
105-115
Published: August 30, 1992
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A cantilever beam-column subjected to completely reversed tip deflection cycling with continuously increasing amplitude under constant axial compression consecutively exhibits a sequence of symmetric steady states, a sequence of asymmetric steady states and finally a divergent behavior. The first critical point, at which a transition from a symmetric steady state to an asymmetric steady state occurs has been named the symmetry limit and the symmetry limit theory has been established by the present authors. The second critical point, at which the deflection divergence occurs, is referred to as a steady-state limit. This paper presents a new theory for predicting the steady-state limit of a bi-linear strain-hardening sandwich beam-column model. A Steadystate limit solution can be found as the first limit point of 〜he steady-state path, which can be traced by a step-by-step analysis based upon a set of linearized equations for the incremental variation of steady state.
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Tetsuo YAMAKAWA
Article type: Article
1992Volume 438 Pages
117-126
Published: August 30, 1992
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The beam theory for a straight uniform bar of narrow rectangular cross section is discussed by using the orthotropic elastic plate (Scheibe) theory and Airy's stress functions in this paper. The Bernoulli-Euler hypothesis in the elementary beam theory is corresponding to the following assumptions of elastic moduli in the orthotropic elastic plate theory. Namely, the transverse shear elastic modulus is infinity as well as the transverse normal elastic modulus, and Poisson's ratios are zero. In a similar way, an equivalent beam theory including the effect of transverse shear deformation and warping can be obtained. On the other hand, Heki presented an analytical solution of the cantilever by using the theory of orthotropic plate (Scheibe). This analytical method is different from the proposed method. Therefore, in this paper a detailed comparison of the accuracy and mechanical property is made through calculation of the cantilever.
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Koji TOMINAGA, Haruyuki YAMAMOTO, Hiroshi YAMASHITA
Article type: Article
1992Volume 438 Pages
127-136
Published: August 30, 1992
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The purpose of this paper is to investigate the effects of pile head condition and pile length on the behavior of laterally loaded piles in sand. The tests were carried out on single piles by using test apparatus which was especially desinged to apply both of fixed and free head conditions. Based on the results of the model tests, Broms' assumption of the ultimate soil resistance equal to three times the Rankine passive pressure for sand is examined, and classifying into "long pile" and "short pile" modes in the method of the estimating ultimate lateral resistance of single piles is also discussed.
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Kuniyoshi INA, Hideaki KISHIDA
Article type: Article
1992Volume 438 Pages
137-146
Published: August 30, 1992
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Three types of pull-out field tests were carried out to examine the performance of a closed-form solution in estimating the displacements of piles in cohesive soil subjected to regular cyclic axial loading. The test program included static loading, creep loading and cyclic loading. Discussion was focused on the interpretation of the static loading test results. The procedures are proposed to estimate the pile displacement under cyclic loading from the static loading test results. The results indicate that the calculated displacements of piles subjected to cyclic pull-out loading are in good agreement with the measurements.
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Toshiro SUZUKI, Toshiyuki OGAWA, Kikuo IKARASHI
Article type: Article
1992Volume 438 Pages
147-155
Published: August 30, 1992
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The plate in a structural member is restrained against buckling by the effect of the intersecting plate. It is recognized・ that this resistance of an element depends on the geometry of an intersecting plate. However, it is considered that the material properties of an intersecting plate is a problem one should not ignore. And it has been almost ignored. As the object.of this study, short-column subjected to axtial compression have been chosen, we have investigated the constraint effect of hybrid H-shaped members on local buckling and the plastic local buckling strength; the deformation capacity and the slope of strength inferiority.
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Koji OGAWA, Yoshiaki KUROBANE, Minoru YAMANARI
Article type: Article
1992Volume 438 Pages
157-164
Published: August 30, 1992
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The effective column length and buckling strength of tubular truss members are disscussed based on the experimental results reported in the previous paper (Part 1). Significant conclusions drawn from this study may be summarized as follows : (1) Axial forces of members can be calculated assuming that joints are hinged until one of the web members buckles. (2) Buckling loads evaluated from the test agree well with results of a theoretical analysis, which is based on the tangent modulus theory ignoring secondary bending moments. (3) The, buckling strength can be predicted with sufficient accuracy by using effective length factors determined by the elastic analysis unless the stiffness of joints deteriorates due to extensive yielding.
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Takuji HAMAMOTO, Yasuo TANAKA
Article type: Article
1992Volume 438 Pages
165-177
Published: August 30, 1992
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Coupled free vibrational characteristics of the large-scaled circular island which is floating on the sea of finite depth and anchored by tension-legs to the seabed are investigated. Hydrodynamic pressure acting on the wetted surface of the island is obtained in closed form oh the basis of a linear potential flow theory. The frequency equation governing the motion of the island-anchorwater coupled system is derived and solved by Rayleigh-Ritz method. Numerical examples are presented to illustrate the variation in coupled free vibrational characteristics due to the,island thickness, water depth and anchor arrangement and stiffness.
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Article type: Appendix
1992Volume 438 Pages
App2-
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Article type: Cover
1992Volume 438 Pages
Cover3-
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